EXTERNAL GUIDE INTERNAL GUIDE HOME THEATRE SYSTEM 5.1 A Report submitted by KOUSHIK NARAYAN.G RAHUL SIDDHARTHA.T VIGNESH.J Under the guidance of EXTERNAL GUIDE INTERNAL GUIDE MR.SALIM MRS.HELINA RAJINI SURESH M.E

SYSTEM ANALYSIS DEFINITION: “System used to achieve theatre acoustical effect at home” EXISTING SYSTEM Generally Home Theatre Systems are designed to transfer the audio signals from one or more DVD’s to the six speakers including the subwoofer. For this process amplifiers and low pass filters are used along with channel selection switches.

NEED FOR THE NEW SYSTEM The existing Home Theatre Systems are designed such that they can handle only DVD inputs and they have limited power output . A Home Theatre System should be capable of transferring two channel Stereo input signals to the 5.1 speakers along with the DVD output signals. The new systems should support high output power.

SYNOPSIS With Home Theater System 5.1 one can enjoy the real acoustical effect as that of a theater in one’s own living place. The main objective of our project is to design and develop a Home Theater System 5.1 with a DVD input and a 6 channel output. In this particular Home Theater System 5.1 we use PIC16C72 which acts as an interface and as a switch between the remote and the volume control IC NJW1153. Based on the functions selected PIC will generate a control data which is given to NJW1153. An 8 bit A/D converter present in the PIC16C72 is used to convert analog signals from the voltage divider (enables the characteristics) circuit into control data in the digital format. Based on the input control data the NJW1153 performs functions like volume control, tone control and Input selector gain control on the selected input channel.

The input channel may be any one of channel A (5. 1), channel B (5 The input channel may be any one of channel A (5.1), channel B (5.1) or the stereo input (2 channel). The output signals from NJW 1153 are amplified using TDA 7265, which is a class AB Dual power amplifier and are given to 5.1 speakers. In case of subwoofer a II order analog Butterworth low pass filter is used for producing low frequency signals (160Hz) prior to amplification. The main idea in designing this system is to connect the two channel stereo input along with the DVD inputs to the 5.1 speakers via NJW 1153.

SYSTEM SPECIFICATION BLOCK DIAGRAM CH.B 2 CH.STEREO VOLTAGE DIVIDER CIRCUIT PIC 16C72 POWER SUPPLY NJW1153 LED DISPLAY AMP LPF CH.A 6 CHANNELS

Features of PIC 16C72 It is nothing but Peripheral Interface Controller. Acts as an interface and as a switching circuit between the remote and the volume control IC NJW1153. Only 35 single word instructions All instructions are single cycle (200 ns) except for program branches which are two cycles. Operating speed DC – 20 MHZ clock input DC 200 ns instruction cycle A/D module.

Features of NJW1153 NJW 1153 is a 6 channel electronic volume IC. It includes input selector, tone control, volume, mute, input selector gain control, volume output gain control and 3 REC outputs. Each mode and conditions are set by the 3 wired serial control data. FEATURES Operating voltage ±4.5 to ±7.5V Input Selector (x 8) REC output ( x3) Input Selector Gain Control Gain : 0/-3/-6/-9/-12dB Volume Output Gain Control Gain : 0/+3/+6/+9/+12/+15/+18dB Volume 0 to -100dB/1dBstep, MUTE Tone Control (Tr & Bs) 0 to ±10dB/1dBstep Subwoofer output addition to L, R channel output Subwoofer output ON/OFF control

The three signals namely REQ, SCK and data are transmitted from PIC 16C72 microcontroller to the NJW1153 IC via pin 31, 30, 29 respectively. The clock signal is enabled 0.8 μs later than REQ signal. Each bit of the data is transmitted during the negative edge of the clock cycle. Thus 16 bit data is transmitted and after transmitting the entire data.

PIC as a switching circuit There are three control signals from the microcontroller to the NJW1153 IC. The control signals are REQ SCK DATA Depending upon the control data the operations like Multi channel selection Input selection Tone control treble Tone control bass Volume control for 6 channel(5 Speakers and 1 subwoofer) are performed.

Control data of NJW1153 is constructed with 16 bits. D0-D3 bits are used for indicating chip address. D4-D7 bits are used for selecting address. D8-D13 bits are used as data bits. The selected address ranges from 0000 to 1001. Volume control one is selected for adjusting the volume of channel 1. Similarly volume control for all these six channels can be selected using ‘select address’ bits as shown.

The input selector gain control & the volume output gain control are selected if the selected address is 0110. Similarly for the select address of 0111.Tone control treble is selected and for 1000 tone bass is selected. When the select address is 1001 input selector and multi channel selector is selected.

TONE CONTROL-TREBLE/BASS

MULTICHANNEL SELECTION &INPUT SELECTION The multi channel selector selects the Two channel input signal (stereo inputs) Multi channel input signal A Multi channel input signal B

AMPLIFIER SECTION The audio signals that are received from the DVD inputs after passing the NJW 1153 IC is amplified using TDA 7265 before being fed to the 5.1 speakers. DESCRIPTION The TDA7265 is class AB dual Audio power amplifier. One TDA 7265 amplifier is capable of amplifying signals that are destined to two speakers. Hence six speakers in 5.1 system can be amplified using three amplifiers. The other features supported by this TDA 7265 are: Wide supply voltage range (up to ±25V ABS Max.) High output power Mute (pop free) Short Circuit Protection Thermal Overload Protection

FILTER CIRCUIT SECOND ORDER ANALOG BUTTERWORTH LOWPASS FILTER The filter is designed for a cut off frequency of 160 Hz and the gain of the filter is found to be -27.5 dB. FC=160 Hz, WC = 2fC=1004.8rad/sec Let c=.33F, R1=5.128k, Rf =3k On substituting in Vo / Vin = Ao (1/R2C2) S2 + (3 – Ao)s + 1 RC R2c2 Gain in db = 20 log |V0| |Vin| Gain= -27.5 dB

FLOW CHART YES NO NO YES POWER ON DEFAULT CHANNEL A CHANNEL SELECTION CHANGE CHANNEL UPDATE NJW1153 CHANGE BASS VOLUME TREBLE POWER ON YES NO NO YES

2 channel stereo input can be connected to Home Theater System 5.1. CONCLUSION FEATURES 2 channel stereo input can be connected to Home Theater System 5.1. LED display to indicate the status of the device. Provision of Input Selector Gain control and Volume output Gain control. ADVANTAGES The very best advantage is that the 2 channel stereo input can also be connected the 5.1 speakers along with other DVD inputs. The power output is very high compared to other systems (5000 watts). Treble, bass, volume control is performed using NJW1153 & PIC 16C72. Voltage divider circuit is designed to produce unique voltage for each parameter.

THANKYOU